Related

London's new Conservative Party mayor, Boris Johnson, once told Britons that "voting Tory will cause your wife to have bigger breasts, and increase your chances of owning a BMW M3." It's unlikely, though, that this extravagant promise framed the expectations of the voters who queued on May 1 to cast their ballots in elections for London's City Hall. London followed the rest of England and Wales in handing the conservatives a remarkable victory in nationwide local elections, adding 256 new council seats and winning control of 12 additional councils.

When the results were announced just before midnight on Friday, the rumpled victor looked momentarily stunned by a victory over Labour incumbent Ken Livingstone that few, even among his most ardent supporters, imagined possible at the start of the campaign. "I do not believe London changed into a Conservative city overnight," he said in his acceptance speech, "but the Conservatives have changed again into a party that can be trusted." As recently as last September, opinion polls gave Labour an 11-point lead over the Conservatives, and a projected 44% share of national votes compared with a Conservative share of 33%. But on Thursday, it was the Tories who garnered a 44% share of the national vote, while Labour trailed the Liberal Democrats on 25% with a miserable 24%. Lingerie stores may not be expecting a surge in demand for larger brassieres, but the Conservative sweep  of which Johnson's victory was the flagship  appears to have dramatically altered the contours of Britain's body politic.

Dogged optimists in Labour's ranks attribute the party's loss of 331 council seats and of London's City Hall to mid-term doldrums. They point out that British voters often use municipal elections to deliver a sharp kick to the party in power, before returning the incumbents to office at the next parliamentary elections. In 1986 the Conservatives suffered eye-watering losses in local elections; a year later their leader Margaret Thatcher won her third term as prime minister. Tony Blair presided over a rout for Labour at municipal polls in 2004, but secured his third term in Downing Street the following year. Labour has now been in power since 1997 without interruption. No wonder the electorate is restive.

Such attempts at optimism in Labour circles overlook a key fact: The current Prime Minister, Gordon Brown, took over from Blair only last June, enjoying an early bounce in popularity among voters who had tired of his predecessor's easy charm and who blamed him for drawing Britain into America's Iraq debacle. In September, after Labour had enjoyed its most harmonious annual party conference in years, Brown's advisers urged him to call a snap election to secure his own mandate. Instead, amid signs of a small upturn in Conservative support, Brown dithered, then denied well-sourced rumors of election plans. His reputation for firm leadership was badly dented. His other boast  that as Chancellor of the Exchequer, he had steered Britain to stability and prosperity  has rung increasingly hollow as the economy has felt the pain of the international credit crunch. Labour's drubbing at the polls came as little surprise after months of criticism leveled at Brown, much of it from his own colleagues. As the scale of the losses became apparent, Brown answered questions from journalists at Downing Street. "It was a disappointing night," he said with impressive understatement, adding "The test of leadership is not what happens in a period of success but what happens in difficult circumstances."

The Prime Minister may be tempted to reassert his authority by reshuffling his Cabinet or unleashing a new torrent of policies. But he also faces another electoral test, a byelection in Crewe and Nantwich in northwest England on May 22, to replace veteran Labour MP Gwyneth Dunwoody, who died last month. And Westminster has been buzzing for weeks with rumors of plots to replace Brown with a younger, sharper leader such as the Foreign Secretary David Miliband or Education Secretary Ed Balls.

Internecine warfare in Labour ranks inevitably delights the Conservatives. "We in the Tory party have become used to Papua New Guinea-style orgies of cannibalism and chief-killing, so it is with a happy amazement that we watch as the madness engulfs the Labour party," quipped Johnson during a 2006 outbreak of Labour infighting. It was a classic Johnsonian gaffe, and he subsequently apologized for any offence to Papua New Guinea.

As London mayor, it may be harder to shrug off such undiplomatic turns of phrase. Still, as Conservative Party leader David Cameron noted, Johnson's mayoral victory, and the Conservatives wider success in England and Wales, signals "not just a vote against Gordon Brown and his government," but "a vote of positive confidence in the Conservative party." With parliamentary elections due by May 2010 and the Conservatives suddenly looking like the favorites, Cameron and his colleagues have to retain the voter confidence expressed on Thursday. And with the London's City Hall now a showcase for Conservative government in action, Cameron will be hoping that Johnson is able keep his sometimes maverick exuberance  and talent for politically incorrect utterances  in check.